Caster



July 25, 1933. A CURRlE 1,920,004

CASTER Filed May 2, 1930 ogg/5.4

Iatented Jul-y 25, `1933i Y y l v I Lezama y l IIUGII A. CURRIE, or CHICAGO, ILLIIvoIs'4 Application ined May 2,

My invention relates to casters,and is concerned more particularly; with casters for heavy duty service, suchas, for example, for facilitating the movement of steel containers suchas are now utilized by the rail! roads for the'transportation of freight and which are moved to and from the specially designed flat-ears that carry a number-of such containers. This caster is also adapted to various other uses, such asfor facilitating the movement of portable warehouse trucks and the like.

One of the objects of my inventionV4 is to provide a caster of great strength and durability and which possesses desirable flexibility in its operation. y

Another object of my invention is to produce a caster of the double wheel type and in which the load supported by such caster will be equally distributed between both of the wheels when operating over relatively rough surfaces, under normal conditions. This I accomplish by providing the caster with a yoke of such a construction as will allow the `aXle of the wheels Vto swing angu` larly in a vertical plane and thereby enable the caster wheels to assumediiferent positions relative to a horizontal plane, such a situation occurring when one of the wheels engages an obstruction or depression in the surface over which the wheels are traveling. In present casters of the two wheel'type the caster 'wheels swivel about a vertical aXis only, with the result thatthe entire load is transferred from one wheel to the other when lthe casters travel over uneven surfaces.

A further object of my invention is to provide the caster with a supporting plate or base'that is adapted to serve a double 40 purpose. The supporting plate is ,adapted to be used as the usual mounting means for the caster assembly and is also lprovided with a bearing boss which is adapted to guide and limit the movements of the yoke member of the caster, as `will be hereinafter fully described. l

Otherl objects and advantages will appear from the following detailed description, reference being had to the accompanying drawing.

1930. Serial No. 449,158.

In the drawing: f

Figure 1 is a front elevational view of the caster;

Figure 2 is a side elevational view of the caster; Y

lFigure 3 is a plansect'ion taken alongv the line 3 3 of Figure 2 illustrating the relation of the depending bearing boss of the supporting plate to the yoke member of the caster; 6o

v Figure Il is a vertical section through the castertaken -alongfthe line 4-t of Figure 3; and

Figure 5 is a horizontal section through the central arm of the yoke member illustrating modified means for retaining the yoke member and its associated parts in operative relation with the supporting plate and with the king pin or post carried thereby. 70

In the particular embodiment of my invention illustrated in the drawing, the structure comprises a mounting or supporting plate 6, a vertical king pin or post 7 carried a thereby, a wheel carrying frame or yoke 8, an aXle 9, and a pair of wheels or rollers 10 which are mounted upon the axle. The supporting plate 6 is provided with a depending bearing boss 11 of cylindrical shape which extends into'an opening 12 of approxi 80 imately elliptical shape formed in the upper portion of the wheel carrying frame or yoke 8 and provides a ybearing surface for controlling the swiveling and lateral movement of the yoke member. The king pin or post 7 is provided with a hemispherical head 13 at the lower end of a reduced shank portion 14, and the post is securely fastened in the supporting plate G in any well known man-y ner, preferably by shrinking the supporting plate onto the post. The supporting plate and the post constitute the stationary members of the caster.

The wheel carryingl frame or yoke 8 comprises a head portion lla having the opening 12 therein, and provided with depending aXle carrying arms 15 and 16, which arms are provided at their lower ends with aligned openings in which the opposite ends and center portion of the axle' 9 are 100 mounted. The central armz16` of the yokethe.side-.thrust"of-thezallead of the carrying member is ofV greaterA cross-sectional area than either of the arms 15, smceit 1s` this particular arml which must sustain and carry the greater'portion of the load which is transmitted tothe post 7, the latter haveA ing its hemispherical head 13 bearing and operating within socket `17 provided in arm 16. As is clearly shown Vin Figure "4,1theV lower surface` otboss 11 `isspaced abovev socket 17 and is out ot contact with "the advantageous as f wheel frame. This is avoiding objectionable friction while also eliminating Vpossibility of binding between the lower surface of the bossand the wheel frame. The king pin or post 75 is Vlocated centrally .of .the caster and directly above the axle and the caster is steered by means of a tongue 18 which is jtorined integrally with the arm 1'6. v.

The carrying frame or yoke. 8 is -held in operative relation to the stationary elements ofj thecaster in any preferred manner as by `means of the dog-pointed screws 19 carried by the arm 16 and projecting into the socket '(17 above headv13. In the event that the vsupporting plate and its associated partsV should be raised or lifted, the carrying frame andits several parts will be retained esv in ltheir normal operative relation to the supportingplate andpos't by reason of the contact of the screws 19 lvviththe shoulder 20 of the hemispherical head 13.

It is obvious vthat there arevarious ways in which the wheel carrying Jframe may be retained in its coacting relation'with-the supporting plate and post, and another en bodiment oi such a means has been illus-r trated in Figure 5. Bolts 21 extendjtransversely of the arm' 16 andare .disposed 4parallel to the.v axis ofgthe axle 9. 'Ihese boltspass directly over theshoulder 2()` of the hemispherical head13, and are slightly spaced trom said shoulder in order to elimi nate the possibility of the shoulder striking Y the bolts when. thek wheel carrying frame is thrown out of. its normal position due vto one of the wheels 10 passing over an 4obstruction.

In casters duty service, a supportingplate kof the par# Vticular construction embodied in my invenf` tion is of paramount importance..` Referring to Figures and 45- it is apparent that thedepending bearing boss 11V isthe guiding and limiting 'element which` controls the various movementsof the frame carrying member, such movements beingV resolved into purely swivelingmovementoi1 the caster, purely lateral Vmovement of the. swinging carrying trame by reason of the elongated opening 12 therein, or any other combined p movements arising outof the lateral swinging of the carrying trame and the swiveling.

action ofthe caster. l In all such movements vwhich are adaptedjtor heavy.'

framed is directly imparted to the bearing boss 11,110 matter what position the'carryling trame'may assume.;V In .this-manner it is seen thatthe bearingboss 11 acts not only in the `capacity of' a guiding Vand limiting means, but also acts as as hielding means for protectingthe king pin or post 7 from the laterallyV impartedi'orceswhich would set i up excessivenslf'iearing stresses in the post member it thebearing boss of the support ing plate were not interposed between the carrying frame and the post. The boss 11 correspondsindiameter to the shorter axis of opening 12,*as isuclearly shown in Figure 3. The' boss .andthe surroundinoiwall'of the opening cooperate toV hold the wheel vframe against. objectionable rocking movement on the axis of the wheel,1'while per- `mitting y limited Arocking movementof the ktrame parallel to this aXis,the boss serving t-o guard effectivelyv the post 7 against ,shearing stresses incident to rockin move- *and that it is possiblevto vary thejconstructionfthereoi:l `without departing `from the `eldV and 'scope' of the invention, and there! `tore, I do not wish to be strictly limited to the particular caster construction disclosed in `the"drawing, except insofar as the appended claims are so limited. What I claimpis:

, 11"In `combination in a caster structure, a

supporting plate provided with an integral dependingvcylindrical boss, a post secured in and extending downwardly from the boss, a wheel frame and wheels mounted coaxially thereon, and aLV universal bearing connection between the lower end of the post and the frame between said wheels, the axis of the said trame being provided with an` elliptical opening disposed with its longer'a'xis parallel to the wheel axisandthe boss extending about thepost and intov said opening andl cooperating with the surroundingwall thereof to limit. rocking movement of the vwheel framefthe bossfguarding the post against shearing` stresses 'incident to rocking of the frame.

2. In combination in a caster structure, a supporting plate provided with a depending. cylindrical boss rigid with the plate, a post secured to and extending downwardly subjected to the 'compresf .post being radial of the axis of the wheels,

CTI

from the boss concentrically therewith, a Wheel frame comprising a central arm and two end arms, wheels mounted coaxially in the frame between the central arm and the end arms thereof, a universal bearing connection between the lowerrend of the post and said central arm, the post being radial to the wheel axis, said frame being provided with an elliptical opening and the boss extending about the post and into said opening, and a steering arm extending from said central arm of the frame.

3. In Combination in a easter structure, a supporting plate provided with an integral depending boss, a post secured in and ex- 

